When people think about physics, several things tend to come to mind, especially if they have never studied the subject. One thing that tends to come to mind is force.  Others are energy and power.  Names like Newton and Einstein also tend to be mentioned. We have spent a fair amount of time working on physics so far in this course, but we have yet to mention any of these things! This is about to change....

Isaac Newton (1642 - 1727) is considered to  be one of the greatest scientists of all time. When he was still a young man, he invented the calculus, and over a period of about 20 years he developed what are now known as  Newton’s three laws of motion, along with the Universal Law of Gravitation.  He also realized that sunlight is really composed of pure colors, and dabbled in chemistry and alchemy.

In this lecture, we will be introduced to Newton’s three laws of motion, and we will start seeing how they can be applied to solving basic force problems. In this lecture and the next we will be learning about some fundamental forces that will enable us to tackle more realistic problems. Then, Lecture 10 will apply all of our understanding of forces and motion to the straightforward, but often counterintuitive, study of circular motion.

At the root of Newton’s laws is, of course, the concept of force.  As we saw in Lecture 5, we may think of a force as that thing that causes an object’s motion to change — that is, a force is that which causes an object to accelerate.  We will see the intimate  relation between force and acceleration in Newton’s second law.

Let’s now proceed to our formal discussion of Newton’s three laws.